Featured Image Hypothermia CXL

Is it useful to cool the cornea during cross-linking?

Is it useful to cool the cornea during cross-linking?

The researchers at ELZA are constantly trying to improve corneal cross-linking. Back in 2013, we identified that oxygen is an essential component of the cross-linking reaction, and its availability limits the rate at which the cross-linking reaction proceeds [1]. But when we looked through the literature, we found an interesting phenomenon: lowering the temperature of the cornea, improves oxygen diffusion. This could solve a problem that exists when we try to accelerate the corneal cross-linking procedure by increasing the intensity of UV irradiation: oxygen gets consumed at a faster rate, limiting the effectiveness of the reaction. The original cross-linking reaction required 30 minutes of UV irradiation to stiffen the cornea, using 3 mW/cm² UV irradiation, but accelerating this reaction beyond 10 minutes (at 9 mW/cm² irradiation) starts to result in diminishing returns in terms of how effectively the cornea is strengthened.

To find out if this makes a difference, we performed some experiments [2]. We took 112 pig corneas obtained from an abattoir, soaked them in 0.1% riboflavin, and split them into 4 groups: two where we performed accelerated epi-off cross-linking, incubated at either 24°C, or 4°C for 10 minutes, and two non-cross-linked control groups, again, one at 4°C, and the other at 24°C, again for 10 minutes. We then performed some stress-strain measurements 

What did we find? Unsurprisingly, cross-linked corneas were stronger than non-cross-linked corneas. However, we did not observe any additional strengthening effect in the group of corneas cross-linked at 4°C over the corneas cross-linked at 24°C. 

This research was published this month in the journal, Eye and Vision.

Cooling the cornea corneal cross-linking - biomechanical effect of epithelium-off corneal cross-linking

 

 

References

  1. Richoz O, Hammer A, Tabibian D, Gatzioufas Z, Hafezi F. The biomechanical effect of corneal collagen cross-linking (Cxl) with riboflavin and UV-A is oxygen dependent. Transl Vis Sci Technol. 2013;2(7):6.
  2. Abdshahzadeh H, Abrishamchi R, Torres-Netto EA, et al. Impact of hypothermia on the biomechanical effect of epithelium-off corneal cross-linking. Eye Vis (Lond). 2021;8(1):4.2.

 

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Augeninstitut ELZA
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Thomas S.
09:37 07 Jul 21
My left eye had to be operated on because of a cataract. As I had an Artiflex lens implanted a few years ago, it had to... be removed first before a modern lens could be implanted to correct the cataract. Prof. Hafezi treated me in an very competent and friendly manner. I am very happy with the result.read more
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Steven H.A
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Prof. F. Hafezi s expertise is enormous and he has a very pleasant and calm nature which gives the patient... security.Thank youread more
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Totally creepy, very arrogant Prof.He just want your money.It may explain, why this Prof. is not in the center of the... city of Zürich and why he has been thrown away from University of Geneva.read more
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Elena Churilova
10:06 17 Nov 20
At the moment, 3 months have passed since the moment I made laser vision correction in this clinic. and I can say that... I am happy that I chose this particular clinic and Prof. F. Hafezi. The entire staff of the clinic is very friendly, treats patients with sympathy and patience if they are nervous before surgery (my big gratitude to Aida Alili for all support and patience). The doctor Hafezi and other doctors of the clinic are very professional and ready to explain to you as many times as you need. I can only recommend!read more
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